When we say "under 16 years old," is it OK to exchange "under" with "below"? I'm confused the difference between these 2 words.
Thank you for your help.
Though the words under and below are synonymous, the two words do have slightly differing connotations: you will find that below is used to refer to a relative lower position of place or rank.
Though one could say "below the age of xx," it really doesn't sound natural -- at least not to my American sensibilities. With the word age, you'll definitely want to use under. In fact, the compound word underage combines the two.